DNA Match Tying Protest to 2004 Killing Is Doubted

A link between DNA from the unsolved killing of Sarah Fox, a Juilliard student, in 2004 and DNA taken from a chain placed at the site of an Occupy Wall Street action in March may be the result of a laboratory error, according to two people briefed on the investigation.

One of the people, who spoke on the condition of anonymity, said it appeared that the DNA recovered from skin cells on the slain woman’s portable compact disc player and from the chain found this year came from a Police Department employee who works with the Office of the Chief Medical Examiner.

Nonetheless, the renewed focus on a DNA link to the Fox case has drawn attention to the way investigators are now using DNA collection for far more than just the most serious of crimes.

The decision by investigators to search for DNA samples on the chain, which was used to hold open a subway entrance gate, illustrates how such collections have become a routine part of a wide range of criminal investigations.

The expansion of DNA collection at crime scenes in New York accelerated around 2007, when the medical examiner’s office opened a new DNA laboratory on East 26th Street and First Avenue and began building a larger staff, greatly expanding the number of samples it could analyze. It also reflects advances over the years in the ability of investigators to extract DNA from skin cells left behind on surfaces like doorknobs, said Mechthild Prinz, the director of the department of forensic biology in the medical examiner’s office.

The ability to analyze such samples, which are known as “touch DNA,” has allowed investigators to use DNA from scenes where bodily fluids may be absent, Dr. Prinz said. Investigators said that the more heavily the suspect was sweating, the more likely he or she was to leave a useful touch DNA sample.

Photo

Sarah Fox, a Juilliard student, was found strangled in Inwood Hill Park in upper Manhattan in 2004. The killing was never solved.Credit
New York Police Department

In 2011, the city medical examiner’s office issued some 11,000 reports involving DNA collected from crime scenes, compared with about 3,000 in 2006, Dr. Prinz said. Reports generally correspond to a single incident, and may involve multiple samples.

Last year, about 32 percent of the incidents in which DNA was sought were property crimes, primarily burglaries and robberies, Dr. Prinz said. Homicides make up only 6 percent of the incidents from which DNA is sought, and sexual assaults are an additional 20 percent. Recovered weapons are swabbed for DNA, too, and account for about 10 percent of the caseload. The remaining cases, Dr. Prinz said, involved DNA taken directly from known suspects for comparison, as well as an assortment of missing person cases, hate crimes, arsons, and other crimes.

In 2011, the medical examiner’s office entered DNA profiles taken from about 2,050 criminal events that year into the F.B.I.’s DNA database. About 24 percent of those resulted in a match against the DNA profiles of known individuals, she said.

At present, the Police Department’s evidence collection units focus DNA collection on crimes for which the police have no suspect. Because those who commit robberies and burglaries are usually strangers to their victims, DNA is a particularly useful tool with those types of crimes, Dr. Prinz said. For that reason it is unlikely that DNA will soon become a routine part of drug possession cases, where the suspect is already identified by the police.

“We want to focus on the cases where identity needs to be established,” Dr. Prinz said.

Dr. Prinz declined to comment on the Fox case. But an official with knowledge of the matter said that the medical examiner’s office had run the DNA found on the compact disc player and the chain through the office’s employee DNA database more than once.

One person familiar with the investigation said that the DNA came from a supervisor in the Police Department’s laboratory, which is also involved in such testing.

Wendy Ruderman contributed reporting.

A version of this article appears in print on July 12, 2012, on page A19 of the New York edition with the headline: DNA Match Tying Protest To 2004 Killing Is Doubted. Order Reprints|Today's Paper|Subscribe